Highly branched polyamidoamines and their preparation

ABSTRACT

An intralinked polyamidoamine which is nonthermosetting and endcapped. This intralinked polyamidoamine is the reaction product of a dicarboxylic acid or dicarboxylic acid derivative, a polyamine, an endcapping agent, and an intralinker.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of application Ser. No. 08/634,226,filed Apr. 18, 1996, now U.S. Pat. No. 5,786,429.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to highly branched polyamidoamines, and tothe preparation of highly branched polyamidoamines.

2. Description of Background and Other Information

Polyamidoamine-epichlorohydrin resins have been used extensively as wetstrength agents for paper, and for other applications. These resins aretypically prepared in a two step process.

In the first step, a polyamidoamine prepolymer is prepared from a diacid(e.g. adipic acid) and a polyamine (e.g., diethylenetriamine). Then inthe second step, the prepolymer is reacted with epichlorohydrin in anamount equal to or greater than the amount of secondary amine groups inthe prepolymer.

In the latter step, a small amount of the epichlorohydrin reacts toeffect branching of the polymer, accompanied by an increase in molecularweight. However, the majority of the epichlorohydrin reacts with theprepolymer to give reactive functional groups--specifically, eitheraminochlorohydrin or azetidinium.

These wet strength resins can also be used as creping adhesives. Crepingadhesives can also be prepared using lower levels of epichlorohydrin,resulting in lower levels of reactive functionality.

SUMMARY OF THE INVENTION

The intralinked polyamidoamine of the present invention is preferablycharacterized by a highly branched structure that lacks the reactiveintralinker functionality of the wet strength and creping adhesiveresins in the prior art. This highly branched structure results fromreacting a prepolymer of controlled molecular weight--especially, aprepolymer of predetermined low molecular weight--with the requisiteamount of epichlorohydrin or other intralinking agent.

Further, the intralinked polyamidoamine of the present invention is apreferably a nonthermosetting and endcapped intralinked polyamidoamine.Also as a matter of preference, the intralinked polyamidoamine of theinvention is free or substantially free of reactive intralinkerfunctionality.

The intralinked polyamidoamine of the invention preferably comprises thereaction product of reactants which include at least one dicarboxylicacid or dicarboxylic acid derivative, at least one polyamine, at leastone endcapping agent, and at least one intralinker. The at least oneendcapping agent preferably comprises at least one member selected fromthe group consisting of monofunctional amines, monofunctional carboxylicacids, and monofunctional carboxylic acid esters.

Further, the intralinked polyamidoamine of the invention preferablycomprises the reaction product of an endcapped polyamidoamine prepolymerand the at least one intralinker. The endcapped polyamidoamineprepolymer itself preferably comprises the reaction product of the atleast one dicarboxylic acid or dicarboxylic acid derivative, the atleast one polyamine, and the at least one endcapping agent.

Also as a matter of preference, the endcapped polyamidoamine prepolymeris free or substantially free of amine and carboxyl end groups.Additionally, the endcapped polyamidoamine prepolymer preferablycomprises alternating dicarboxylic acid and polyamine residues, andendcaps lacking carboxyl and amine functionality; yet further, theendcaps are preferably amide endcaps.

The endcapped polyamidoamine prepolymer preferably has a DP_(n) of about2 to about 50--more preferably about 3 to about 25, and still morepreferably about 3 to about 10. Also as a matter of preference, the moleratio of the at least one intralinker, to intralinker reactive aminegroups in the endcapped polyamidoamine prepolymer, is between about 1/21/(DP_(n) -1)! and about 1/(DP_(n) -1).

The invention also pertains to a process for preparing an intralinkedpolyamidoamine polymer which is nonthermosetting and endcapped. Thisprocess comprises reacting at least one dicarboxylic acid ordicarboxylic acid derivative, at least one polyamine, at least oneendcapping agent, and at least one intralinker.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an idealized representation of the structure characterizingthe intralinked polyamidoamine of the invention --prepared fromdicarboxylic acid or dicarboxylic acid derivative, polyalkylenepolyamine, monoalkanol amine, and epihalohydrin.

FIG. 2 is a graph showing the relationship between actual reducedspecific viscosity, for prepolymer of the invention, and the prepolymertheoretical DP_(n).

FIG. 3 is a graph plotting maximum amount of intralinker againstprepolymer reduced specific viscosity.

FIG. 4 is a graph showing the relationship between maximum amount ofintralinker and 1/(DP_(n) -1) for resins of the invention.

DESCRIPTION OF THE INVENTION

The dicarboxylic acids and dicarboxylic acid derivatives of theinvention comprise two amidization reactive carboxyl (i.e., --COOH)groups.

Suitable dicarboxylic acids for the invention include the C₂ -C₁₂dicarboxylic acids. Particular dicarboxylic acids which are suitableinclude oxalic, malonic, succinic, glutaric, adipic, pilemic, suberic,azelaic, sebacic, maleic, fumaric, itaconic, phthalic, isophthalic, andterephthalic acids.

Suitable dicarboxylic acid derivatives for the invention includedicarboxylic acid esters and dicarboxylic acid halides. Preferredderivatives are the esters.

Dicarboxylic acid esters which may be used include esters of the C₂ -C₁₂dicarboxylic acids, and especially the C₁ -C₃ diesters of these acids.Particular diesters which are suitable include dimethyl adipate,dimethyl malonate, diethyl malonate, dimethyl succinate, and dimethylglutarate.

Appropriate dicarboxylic acid halides include adipoyl chloride, glutarylchloride, and sebacoyl chloride.

The polyamines of the invention comprise at least two amidizationreactive amine groups. Preferably the amidization reactive amine groupsare primary amine groups.

Also as a matter of preference, the polyamines of the invention furthercomprise at least one intralinker reactive amine group. The intralinkerreactive amine groups are preferably secondary and/or tertiary aminegroups.

Suitable polyamines include the polyalkylene polyamines--including thosehaving at least two primary amine groups and also at least one secondaryand/or at least one tertiary amine group. Especially preferredpolyamines, including the polyalkylene polyamines, are those having twoprimary amine groups and also at least one secondary and/or at least onetertiary amine group. Particular suitable polyamines includediethylenetriamine (DETA), triethylenetetramine (TETA),tetraethylenepentamine (TEPA), iminobispropylamine (IBPA),N-methyl-bis-(aminopropyl)amine (MBAPA), and bis-hexamethylenetriamine.

Endcapping agents are understood as including whatever attaches to orreacts with the dicarboxylic acid, dicarboxylic acid derivative, orpolyamine--or attaches to or reacts with dicarboxylic acid or polyamineresidues--and thereby prevents the further reaction of these reactantsand residues. Particularly, it is further amidization reactions of thesereactants and residues which are thusly prevented.

Suitable endcapping agents for the invention include the monofunctionalamines, the monofunctional carboxylic acids, and the monofunctionalcarboxylic acid esters. It is understood that the monofunctional aminesare those amines having only one amidization reactive amine group, thatthe monofunctional carboxylic acids are those carboxylic acids havingonly one amidization reactive carboxyl group, and that themonofunctional carboxylic acid esters are those carboxylic acid estershaving only one amidization reactive ester group.

Suitable monofunctional amines include monofunctional primary amines,including monoalkyl amines and monoalkanol amines, and monofunctionalsecondary amines, including dialkyl amines and dialkanol amines.

Among the monofunctional primary amines which are suitable arebutylamine, ethanolamine (i.e., monoethanolamine, or MEA),cyclohexylamine, 2-methylcyclohexylamine, 3-methylcyclohexylamine,4-methylcyclohexylamine, benzylamine, isopropanolamine (i.e.,monoisopropanolamine), mono-sec-butanolamine,2-amino-2-methyl-1-propanol, tris(hydroxymethyl)aminomethane,tetrahydrofurfurylamine, furfurylamine, 3-amino-1,2-propanediol,1-amino-1-deoxy-D-sorbitol, and 2-amino-2-ethyl-1,3-propanediol. Amongthe monofunctional secondary amines which are suitable are diethylamine,dibutylamine, diethanolamine (i.e., DEA), di-n-propylamine,diisopropanolamine, di-sec-butanolamine, and N-methylbenzylamine.

Monofunctional carboxylic acids which are suitable for the presentinvention include benzoic acid, 2-hydroxybenzoic acid (i.e., salicylicacid), 3-hydroxybenzoic acid, acetic acid, phenylacetic acid, propionicacid, butyric acid, valeric acid, caproic acid, caprylic acid, oleicacid, ortho-toluic acid, meta-toluic acid, and para-toluic acid,ortho-methoxybenzoic acid, meta-methoxybenzoic acid, andpara-methoxybenzoic acid.

Monofunctional carboxylic acid esters which are suitable for the presentinvention include methyl acetate, ethyl acetate, methyl benzoate, ethylbenzoate, methyl propionate, ethyl propionate, methyl butyrate, ethylbutyrate, methyl phenyl acetate, and ethyl phenyl acetate.

Intralinkers appropriate for the present invention include compoundshaving two, or at least two sites which are reactive with intralinkerreactive amine groups in the prepolymer of the invention, and whichthereby connect prepolymer chains to provide the desired branching. Inthis context, the intralinker reactive amine groups are understood asincluding the prepolymer secondary and tertiary amine groups whichthusly react with the intralinkers.

These intralinkers accordingly link the prepolymer to provide the highmolecular weight, highly branched, intralinked polymers orresins--preferably, the high molecular weight, highly branched,intralinked polyamidoamine polymers or resins--of the invention. In thisregard, the intralinking which characterizes the intralinked polymers ofthe invention is the intramolecular connection of prepolymer chains byintralinker; this intralinking does not encompass intermolecularconnections between discrete polymer molecules.

The intralinking of the present invention is accordingly distinguishedfrom crosslinking, which is understood as referring to the indicatedintermolecular connections. In resins of the prior art, compounds whichserve as intralinkers for the present invention can serve to crosslinkpolymer molecules; this crosslinking is absent, or substantially oressentially absent, from the intralinked polyamidoamines of theinvention.

Suitable intralinkers include haloalklyene oxides. These includeepihalohydrins--i.e., epichlorohydrin, epibromohydrin, epiiodohydrin,and epifluorohydrin--and alkyl substituted epihalohydrins. Also includedare 1-bromo-3,4-epoxybutane, chloroepoxyhexane, and iodoepoxyisobutane.Diepoxides, including ethylene glycol diglycidyl ether (i.e., EGDGE) and1,4-butanediol diglycidyl ether (i.e., BDDGE), are also suitable.1,2,7,8-diepoxyoctane, 3-(bis(glycidoxymethyl)-methoxy)-1,2-propanediol,1,4-cyclohexanedimethanol diglycidyl ether, 4-vinyl-1-cyclohexenediepoxide, 1,2,5,6-diepoxycyclooctane, and bisphenol. A diglycidyl ethermay also be used.

Yet additional suitable intralinkers are diacrylates dimethacrylates,diacrylamides, and dimethacrylamides which are reactive, with theintralinker reactive amine groups of the prepolymer, by a Michaelreaction. Examples are ethylene glycol diacrylate, ethylene glycoldimethacrylate, 1,4-butanediol diacrylate, 1,4-butanedioldimethacrylate, tripropylene glycol diacrylate, tripropylene glycoldimethacrylate, triethylene glycol diacrylate, triethylene glycoldimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanedioldimethacrylate, N,N'-methylenebisacrylamide,N,N'-methylenebismethacrylamide, N,N'-(1,2-dihydroxyethylene)bisacrylamide, andN,N'-(1,2-dihydroxyethylene)bismethacrylamide.

The prepolymer of the invention is a preferably a controlled, lowmolecular weight prepolymer. The prepolymer of the invention is alsopreferably an endcapped prepolymer. Yet further as a matter ofpreference, the prepolymer of the invention is a polyamidoamine. Thepolyamidoamine prepolymer of the invention is preferably obtained by apolycondensation reaction of the dicarboxylic acid, polyamine, andendcapping agent.

The diacid, polyamine, and endcapping agent undergo amidization--i.e.,carboxyl groups and amine groups of these reactants react to form amidefunctionalities. In this context, amidization reactions are understoodas including condensation reactions of the diacid andpolyamine--particularly, reaction of diacid carboxyl groups withpolyamine primary amine groups--in formation of prepolymer chains.Amidization reactions are also understood as including reactions ofendcapping agents with prepolymer chain end groups--particularly,reaction of monofunctional carboxylic acid carboxyl groups withprepolymer primary amine groups, and reaction of the amine groups ofmonofunctional amines with prepolymer carboxyl groups--to form endcappedprepolymer.

Further in this context, amidization reactive groups are understood asincluding the carboxyl and amine groups of the diacids, polyamines, andendcapping agents which undergo the amidization reactions. Particularlyas to the polyamines, the amidization reactive groups are understood asincluding the primary amine groups of the polyamines.

One or more of each of the acid, polyamine, and endcapping agent may beemployed in the polycondensation; further, one or more dicarboxylic acidderivatives may be used in place of, or in addition to, the dicarboxylicacid. Particularly as to endcapping agent, one or more monofunctionalamines and/or one or more monofunctional carboxylic acids may be used.

The volatility of the endcapping agent should be low enough so that thisagent remains in the prepolymerization reaction at the temperature atwhich the reaction is being conducted. Particularly, when the prepolymeris prepared by thermally driven polycondensation, volatility is asignificant feature of the endcapping agent; in this instance, anendcapping agent of lesser volatility is preferred. The boiling point ofthe endcapping agent should be high enough so that, at the temperaturebeing employed to drive off the condensation product--i.e., water wherea diacid reactant is used, and alcohol in the case of diester--the agentis not also removed.

Considering the foregoing, for diacids--particularly where the diacidand polyamine are adipic acid and DETA--prepolymerization willcustomarily be conducted at about 150°-180° C.--more preferably, about160°-170° C. In this instance the endcapping agent should therefore havea boiling point above 180° C.--or above 170° C., in the case of theindicated 160°-170° C. range--so that it is not driven off with thewater.

Where diester is used instead of diacid, and the resulting alcoholcondensation product is more volatile than water, an endcapping agent ofgreater volatility may be used. Because not as high a temperature isrequired for removing the alcohol, the endcapping agent cancorrespondingly have a lower boiling point without being taken off.

The polycondensation reaction of dicarboxylic acid and/or derivative,polyamine, and endcapping agent thusly provides a prepolymer comprisingpolymer chains which include alternating dicarboxylic and polyamineresidues, and which are terminated by endcaps. It is understood that thedicarboxylic and polyamine residues are the units remaining after theamidization reactions of dicarboxylic acid and/or derivative withpolyamine to form the prepolymer chains, and that the endcaps also areresidues--i.e., the units remaining after reaction of endcapping agentwith prepolymer chain end groups.

By virtue of the presence of the endcapping agent in theprepolymerization polycondensation reaction of the invention, theprepolymer is thusly endcapped. Amine and carboxyl functionality aretherefore preferably absent, or at least essentially absent or at leastsubstantially absent, from the chain ends of the endcappedprepolymer--i.e., the endcapped prepolymer is free, or at leastessentially or at least substantially free, of amine and carboxyl endgroups.

Accordingly, the prepolymer of the invention is preferably characterizedby endcaps lacking both carboxylic and amine functionality. Themonofunctional amine endcapping agents react with carboxyl groups of theforming prepolymer, while monofunctional carboxylic acid endcappingagents react with prepolymer amidization reactive amine groups; in bothinstances, the result is an amide endcap. The endcaps of the prepolymerare therefore preferably amide endcaps.

It is understood that the polyamidoamine prepolymers or intralinkedpolyamidoamines are "endcapped" when they comprise an endcap, asdiscussed herein. Particularly, they are endcapped when they comprise aresidue (reaction product) of an endcapping agent.

The molecular weight of the prepolymer of the invention can becontrolled by the relative amounts of the dicarboxylic acid, polyamine,and endcapping agent employed in the polycondensation reaction.Particularly, it is the use of endcapping agent which allows for controlof the prepolymer molecular weight.

In this regard, where the endcapping agent is a monofunctionalcarboxylic acid, during prepolymerization it is competing with thedicarboxylic acid to react with the polyamine, and with amine end groupsin the growing prepolymer chain. If it is the diacid which reacts,polymerization continues; however, amidization with the endcapping agentforms an endcap, thusly stopping the chain growth. Conversely, if amonofunctional amine is the endcapping agent, competition is with thepolyamine reactant.

The more endcapping agent which is employed relative to its competingreactant, the lower will be the molecular weight of the resultingprepolymer. Particularly, the more one of the diacid end polyaminereactants is replaced by its competing endcapping agent, the lower theprepolymer molecular weight will be. In this manner, a prepolymer ofpredetermined molecular weight can be provided.

The relative proportions of diacid, polyamine, and endcapping agentemployed in the prepolymerization reaction are preferably such that thetotal number of amidization reactive carboxyl groups contributed bythese reactants is equal, or at least substantially equal or essentiallyequal, to the total number of amidization reactive amine groups whichare contributed; accordingly, the ratio of the total number of theseamidization reactive carboxyl groups to the total number of amidizationreactive amine groups is preferably 1:1, or about 1:1. Thiscorrespondence between amidization reactive carboxyl and amine groups isnecessary so that endcapping of the prepolymer will likewise becomplete, or at least substantially complete or essentially complete.

Therefore, where the endcapping agent is a monofunctional carboxylicacid, the relative proportions of diacid, polyamine, and endcappingagent will be such that the total number of amidization reactivecarboxyl groups contributed by the diacid and the endcapping agenttogether will be equal, or at least substantially equal or essentiallyequal, to the number of amidization reactive amine groups contributed bythe polyamine. And where the endcapping agent is a monofunctional amine,the relative proportions of diacid, polyamine, and endcapping agent willbe such that the total number of amidization reactive amine groupscontributed by the polyamine and the endcapping agent together will beequal, or at least substantially equal or essentially equal, to thenumber of amidization reactive carboxyl groups contributed by thediacid.

Specifically, taking a 1:1 molar ratio of diacid and polyamine as thestarting point, preferably two moles, or about two moles, of theendcapping agent are employed in place of one mole of whichever of thediacid and polyamine is its competing reactant. Accordingly, if theendcapping agent is a monofunctional carboxylic acid, it should beconsidered that two moles, or about two moles, of this acid is replacingeach mole of the diacid in a 1:1 molar ratio of diacid and polyamine.Conversely, if the endcapping agent is a monofunctional amine, it shouldbe considered that two moles, or about two moles, of this amine isreplacing each mole of the polyamine in the indicated 1:1diacid/polyamine molar ratio.

The molecular weight of the prepolymer of the invention can be measuredby the reduced specific viscosity (RSV). Prepolymer molecular weight canalso be expressed in terms of DP_(n), which is the number-average degreeof polymerization, or the average number of subunits in a polymer chain.Particularly for the endcapped prepolymer of the present invention, thesubunits include the following:

the amidoamine subunits, each of these units being a single diacidresidue linked to a single polyamine residue; and

taken as one subunit, the two endcaps and the single excess residuewhich remains after apportioning the other diacid and polyamine residuesinto amidoamine subunits.

The DP_(n) of the prepolymer of the invention is additionally defined bythe formula

    DP.sub.n =(1+r)/(1-r)

where r is defined as the ratio of the monomer units, and is itselfcalculated as follows:

    where A>B, r=A/(B+2C)

    where B>A, r=B/(A+2C)

The quantity r is always less than 1.

A, B, and C represent the molar proportions of diacid, polyamine, andendcapping agent, respectively. These quantities are further defined bythe following relationships:

    where A>B, C=2(A-B)

    where B>A, C=2(B-A)

Where A is greater than B, C is monofunctional amine; where B is greaterthan A, C is monofunctional carboxylic acid. A and B are never equal.

The prepolymer of the invention has a DP_(n) preferably of about 2 toabout 50, more preferably of about 3 to about 25. As a matter ofparticular preference, the DP_(n) of the prepolymer of the invention isabout 3 to 10.

Where DP_(n) =2, r=1/3 (0.333). Where DP_(n) =50, r=49/51 (0.961). Table1 below shows the different values of r, A, B, and C for DP_(n) equal to2 and DP_(n) equal to 50--depending upon whether there is a molar excessof diacid to polyamine (i.e., A>B), with the endcapping agent thereforebeing monofunctional amine, or a molar excess of polyamine to diacid(i.e., B>A), with the endcapping agent therefore being monofunctionalacid.

                  TABLE 1    ______________________________________                 DP.sub.n r      A      B    C    ______________________________________    Monofunctional amine;                 50       0.961  1.000  0.986                                             0.028    A > B    Monofunctional amine;                 2        0.333  1.000  0.333                                             1.334    A > B    Monofunctional acid;                 50       0.961  0.986  1.000                                             0.028    B > A    Monofunctional acid;                 2        0.333  0.333  1.000                                             1.334    B > A    ______________________________________

The amine functionality-free and carboxyl functionality-free endcaps forthe prepolymer are preferred to provide the desired high molecularweight, highly branched (i.e., hyperbranched) polymers--preferably, highmolecular weight, highly branched (i.e., hyperbranched)polyamidoamines--of the invention. Amine functionality in the chain endgroups of the completed prepolymer is disadvantageous because amine endgroups will react with the intralinker to give chain extension, ratherthan the desired branching. This chain extension would thusly cause theresin final product to be excessively linear.

Further, carboxyl functionality in the chain end groups of the completedprepolymer also is disadvantageous because carboxyl end groups willreact with polymer chain secondary amines. The likely result will begelling; in any case, the final product would be unsuitable.

It is thusly preferred that control of prepolymer molecular weight beaccomplished by endcapping, as discussed herein. If instead of includingendcapping agent in the polycondensation reaction, the molecular weightof the prepolymer is controlled by limiting the amount of diacidreactant relative to polyamine (i.e., employing an excess of polyaminein the prepolymerization), then the resulting prepolymer will becharacterized by a preponderance of primary amine end groups.Conversely, if prepolymer molecular weight is controlled by limiting theamount of polyamine reactant relative to diacid (i.e., employing anexcess of diacid in the prepolymerization), then the resultingprepolymer will be characterized by a preponderance of carboxyl endgroups. The disadvantages of amine and carboxyl end groups in theprepolymer are as has been discussed.

Further, where a low molecular weight prepolymer is provided, it ispossible to obtain a more highly branched, intralinked final resinproduct--particularly, a more highly branched, intralinkedpolyamidoamine resin. specifically, the lower the molecular weight ofthe prepolymer, the greater the amount of branching can be provided inthe final product.

The amount of intralinker used for preparing the intralinkedpolyamidoamine of the invention is that which is sufficient to provide ahigh molecular weight, highly branched resin, but which is also lowenough so that all, or essentially all or substantially all, of theintralinker is serving to intralink prepolymer, or is fullyreacted--i.e., leaving the intralinked resin free, or essentially freeor substantially free, of reactive intralinker functionality.

Expressed in terms of prepolymer molecular weight, the intralinker ispreferably present, in the intralinked polyamidoamine of the invention,in an amount wherein the mole ratio of intralinker, to intralinkerreactive amine groups in the endcapped prepolymer, is between about 1/21/(DP_(n) -1)! and about 1/(DP_(n) -1)!. More preferably, theintralinker is present in an amount wherein the mole ratio ofintralinker, to intralinker reactive amine groups in the endcappedprepolymer, is equal to 1/(DP_(n) -1), or about 1/(DP_(n) -1).

In this regard, the 1/(DP_(n) -1) value, at the upper end of theindicated 1/2 1/(DP_(n) -1)! to 1/(DP_(n) -1)! range, is optimal becauseit represents the highest proportion of intralinker employed with agiven prepolymer molecular weight. At a particular prepolymer molecularweight, the more intralinker which may be employed, the greater thedegree of the desired branching is achieved.

Also as a matter of preference, the intralinker is preferably present,in the intralinked polyamidoamine of the invention, in an amount whereinthe mole ratio of intralinker, to intralinker reactive amine groups inthe endcapped prepolymer, is between about 0.02 and about 0.5. Expressedin terms of mole percent, the intralinker is preferably present, in theintralinked polyamidoamine of the invention, in an amount wherein themole percent of intralinker, based on moles of intralinker reactiveamine groups in the endcapped prepolymer, is between about 2 percent andabout 50 percent.

More preferably, the intralinker is present in an amount wherein themole ratio of intralinker, to intralinker reactive amine groups in theendcapped prepolymer, is between about 0.04 and about 0.5--i.e., about 4to about 50 mole percent intralinker. As a matter of particularpreference, the intralinker is present in an amount wherein the moleratio of intralinker, to intralinker reactive amine groups in theendcapped prepolymer, is between about 0.1 and about 0.5--i.e., about 10to about 50 mole percent.

It is understood that by moles of intralinker reactive amine groups, itis meant the total number of amine groups in the prepolymer that arereactive with the intralinker.

Reactive intralinker functionality is understood as referring tointralinker which is appended to but is not linking prepolymer, becausenot all of the intralinker reactive sites have reacted with intralinkerreactive amine groups of the prepolymer. For instance, whereepichlorohydrin is the intralinker, two possible types of reactiveintralinker functionality are azetidinium and aminochlorohydrin groups.

The lower the molecular weight of the prepolymer, the more intralinkeris required to achieve the requisite high molecular weight throughbranching. However, the maximum amount of intralinker which can beemployed is that which can be reacted with the prepolymer and stillleave the intralinked resin free, or essentially free or substantiallyfree, of reactive intralinker functionality. This maximum amount ofintralinker is also that amount which can be reacted with the prepolymerwithout causing the resin to gel, or without resulting in athermosetting resin.

In this regard, gelling and thermosetting of polyamidoamine resinsresult from the presence of reactive intralinker functionality. Bothgelling and thermosetting entail the formation of intermolecularconnections between discrete resin molecules. Gelling and thermosettingare caused by reaction between reactive intralinker functionality andintralinker reactive amine groups of different resin molecules; thereactive intralinker functionality thusly crosslinks the differentmolecules, and these molecules accordingly form an interconnectedstructure which is insoluble.

Particularly in the case of a thermosetting resin, the act of heatingand/or drying the resin hardens it, as well as rendering it insoluble.In the prior art, resin solutions are acid stabilized, so that heatingwill not gel or thermoset the resin.

In contrast, the intralinked polyamidoamines of the present inventionare nongelling and nonthermosetting. With all--or essentially all orsubstantially all--of the intralinker already reacted to linkprepolymer, the dearth of reactive intralinker functionality precludes,or at least greatly limits, reaction between the discrete resinmolecules. The intralinked polyamidoamines of the invention canaccordingly be redissolved after drying and/or heating.

Reactive intralinker functionality can be ascertained by NMR.Particularly, this analytical technique is suitable for confirming theabsence, or substantial or essential absence, of this functionality fromresins of the invention.

An idealized representation of the structure which characterizes theresin of the invention--where the resin has been prepared fromdicarboxylic acid or dicarboxylic acid derivative, polyalkylenepolyamine, monoalkanol amine, and epihalohydrin--is shown in FIG. 1. Theindicated high branching and lack of reactive intralinker functionalityare displayed in this structure; it is understood that FIG. 1 is notintended to be an accurate representation of the complete molecularstructure of the resin.

To prepare the prepolymer from diacid, polyamine, and endcapping agent,a mixture of these three reactants is heated at a temperature of about160°-170° C. for about 1/2-4 hours, at atmospheric pressure; where areduced pressure is employed, lower temperatures may be utilized. Thispolycondensation reaction produces water as a byproduct, which isremoved by distillation. At the end of this reaction the resultingproduct is dissolved in water at a concentration of about 50% by weighttotal polymer solids.

Where diester is used instead of diacid, the prepolymerization can beconducted at a lower temperature--specifically, about 110° C. atatmospheric pressure. In this case the byproduct will be an alcohol, thetype of alcohol depending upon the identity of the diester. Forinstance, where a dimethyl ester is employed the alcohol byproduct willbe methanol, while ethanol will be the byproduct obtained from a diethylester.

An aqueous solution of the prepolymer is reacted with intralinker toobtain the intralinked polyamidoamine. The prepolymer and intralinkerare mixed with an appropriate amount of dilution water, to provide areaction solution having a concentration of about 30% by weight totalsolids (prepolymer+intralinker). This mixture is then maintained at atemperature of about 25°-80° C.--still more preferably about 50°-70° C.,and most preferably about 60° C.

The viscosity of the mixture is monitored, using Gardner-Holdt viscositytubes. The reaction is continued until viscosity reaches a particularvalue--preferably, "L" on the Gardner-Holdt scale at which point colddilution water is added to end the reaction. Alternatively, the reactionmay be diluted with warm water, with the heating being continued untilthe viscosity again builds to the "L" level; several such iterations canbe performed before the reaction is ended.

The intralinked polyamidoamines of the invention are suitable fortreatment of, addition to, and incorporation with cellulosic and fibrousmaterials, especially cellulosic and fibrous webs, and most especiallypaper. The intralinked polyamidoamines of the invention have particularutility as creping adhesives, wet strength agents, and dry strengthagents for cellulosic and fibrous materials, especially cellulosic andfibrous webs, and most especially paper. They are also useful asretention and drainage aids in papermaking, and can be employed as sizepromoters, emulsion stabilizers, paper coatings, adhesive formulations,flocculants, demulsifiers, and corrosion inhibitors.

The invention further pertains to compositions--including aqueouscompositions--comprising the intralinked polyamidoamines of theinvention. Particularly, compositions comprising the intralinkedpolyamidoamines of the invention are suitable for treatment of, additionto, and incorporation with cellulosic and fibrous materials, especiallycellulosic and fibrous webs, and most especially paper. Compositions ofthe invention--e.g., aqueous solutions of the intralinkedpolyamidoamines of the invention--preferably comprise amounts of theresin which are effective for the intended use.

Particularly, compositions of the invention, and most particularlyaqueous solutions of the intralinked polyamidoanines of the invention,are suitable as creping adhesive, wet strength, and dry strengthcompositions--e.g., for cellulosic and fibrous materials, especiallycellulosic and fibrous webs, and lost especially paper. Thesecompositions comprise amounts of the resin effective for the intended(e.g., creping adhesive or wet strength) function.

Suitable aqueous solutions of the invention include those havingconcentrations of about 1-60% by weight resin. For creping adhesive, wetstrength, and dry strength applications, solution concentrations ofabout 1-40% by weight resin are preferred; concentrations of about 5-35%are more preferred, while the most preferred concentrations are about10-30%.

With regard to creping adhesive applications, the presence of chlorideion can lead to corrosion of the Yankee dryer. Accordingly, resins ofthe invention which are free of chloride ion--e.g., where theintralinker which is employed is a nonchloride, such as in the case ofethylene glycol diglycidyl ether and 1,4-butanediol diglycidylether--are especially advantageous as creping adhesives.

Further, the resins of the invention are particularly advantageous forwet strength applications where repulpability is desired. The cellulosicmaterial with which these resins are thusly used, particularly paper, iseasily repulped, due to the lack of intralinker reactive functionalitywhich would create covalent bonds.

The invention also pertains to cellulosic and fibrous materials,especially cellulosic and fibrous webs, and most especially paper,comprising the intralinked polyamidoamines of the invention. Thesematerials preferably incorporate amounts of the resin effective for theintended function.

When employed as wet and dry strength agents, the resins of theinvention are preferably present in amounts of about 0.1-5% by weightresin, based on the dry weight of the cellulosic material. The quantityof resin present depends upon the degree of wet and/or dry strengthdesired in the finished product, and on the amour: of resin retained bythe cellulosic fibers.

Compositions and resins of the invention can be employed as wet strengthagents and creping adhesives according to the standard methods as theseare known in the art. Particularly for wet strength applications, theagents are typically added to the pulp furnish any time before the sheetis formed. In the case of creping applications, the compositions andresins of the invention can be employed as creping adhesives inaccordance with the procedures set forth in Canadian Patent No. 979,579and in U.S. application Ser. No.08/428,287, filed Apr. 25, 1995, whichare incorporated herein in their entireties, by reference thereto.

In this regard, fibrous webs, particularly paper webs, areconventionally subjected to the creping process in order to give themdesirable textural characteristics, such as softness and bulk. Thecreping process typically involves applying creping adhesive--generallyin the form of an aqueous solution or dispersion--to a drying surfacefor the web; preferably, this surface is the surface of a rotatingcreping cylinder, such as the apparatus known as a Yankee dryer. The webis then adhered to the indicated surface. It is subsequently dislodgedfrom the surface with a creping device--preferably, a doctor blade. Theimpact of the web against the creping device ruptures some of thefiber-to-fiber bonds within the web, causing the web to wrinkle orpucker.

The invention accordingly pertains to a process of creping paper. Thecreping process of the invention can comprise the steps of providing afibrous web, and creping this web by applying the intralinkedpolyamidoamine to the web --and/or by applying the resin to a means forcreping the web, and employing this means to crepe the web. Further inthis regard, the creping process of the invention can include the stepsof applying the intralinked polyanidoamine to a drying surface forfibrous web, providing a fibrous web, pressing the fibrous web againstthe drying surface to adhere this web to the surface, and dislodging thefibrous web from the drying surface with a creping device to crepe thefibrous web.

The invention additionally pertains to the making of paper by a processwhich includes addition of the intralinked polyamidoamine to provide wetstrength to the paper. This process can include the steps of providing apaper pulp, adding the resin of the invention to the pulp, forming asheet from the paper pulp after addition of the intralinkedpolyamidoamine, and drying the sheet to form paper.

Further, the invention pertains to a process of repulping paper. Thisprocess can include the steps of providing paper which comprises theintralinked polyamidoamine of the invention, and forming a slurrycomprising water and pulp prepared from the indicated paper. Theinvention further pertains to the process of making paper from pulpprepared according to the foregoing repulping process, and to paper madefrom this pulp.

The invention is illustrated by the following Procedures and Examples;these are provided for the purpose of representation, and are not to beconstrued as limiting the scope of the invention. Unless statedotherwise, all percentages, parts, etc. are by weight.

SYNTHESIS OF THE PREPOLYMERS

Example 1 is a polyamidoamine prepared from adipic acid anddiethylenetriamine, without the endcapping agent of the presentinvention; this prepolymer is included for the purpose of comparisonwith the prepolymers of the invention.

For the prepolymers of Examples 2-15, which are prepolymers of theinvention, the polyamine and the monoethanolamine endcapping agent wereadded to a 2,000 ml. resin kettle fitted with a condenser, Dean-Starktrap, thermocouple, addition funnel, and mechanical stirrer. Stirring ofthis mixture was then initiated, and the adipic acid was cautiouslyadded during the stirring; the temperature of the reaction mixture wasmaintained below 125° C. by controlling the rate at which the adipicacid was added.

After the addition of the adipic acid was completed, the temperature wasraised to 169°-171° C., and maintained in this range for 4 hours. Duringthis period water of distillation was removed through the Dean-Starktrap.

Hot water (˜70° C.) was cautiously added to the product, which wasstirred until the prepolymer was dissolved.

Table 2 below sets forth the amounts of reactants employed in preparingthe prepolymers of Examples 1-15, as well as the actual and theoreticalwater of distillation, the amount of hot water added during thesynthesis, and the solids content of the product. Table 2 also liststheoretical and actual molecular weight values (provided as DP_(n) andRSV, respectively) for the resulting prepolymers.

                                      TABLE 2    __________________________________________________________________________    Synthesis of Prepolymers                                  Theo.                                      Actual                                           Added    Example         Theoretical               Moles                   Moles  Moles                              RSV W. of                                      W. of                                           Hot    Number         DP.sub.n               Adipic                   Polyamine                          MEA (dL/g).sup.1                                  Dist.                                      Dist.                                           Water                                               Solids    __________________________________________________________________________    1    100   3.00                   3.00 DETA                          0.00                              0.1436                                  108 mL                                       97 mL                                           676 mL                                               50.0%    2    5.00  2.00                   1.77 DETA                          0.46                              0.0841                                   72 mL                                       59.5 mL                                           450 mL                                               50.3%    3    9.00  3.00                   2.75 DETA                          0.50                              0.0932                                  108 mL                                      101 mL                                           450 mL                                               59.7%    4    3.67  3.00                   2.25 DETA                          1.50                              0.0685                                  108 mL                                       91 mL                                           650 mL                                               49.7%    5    3.67  3.00                   2.25 DETA                          1.50                              0.0698                                  108 mL                                       99 mL                                           650 mL                                               51.6%    6    3.34  3.00                   2.14 DETA                          1.71                              0.0664                                  108 mL                                       96 mL                                           650 mL                                               50.9%    7    4.33  3.00                   2.40 DETA                          1.20                              0.0745                                  108 mL                                       96.5 mL                                           650 mL                                               51.8%    8    4.33  3.00                   2.40 DETA                          1.20                              0.0751                                  108 mL                                      100 mL                                           650 mL                                               50.7%    9    4.33  3.00                   2.40 DETA                          1.20                              0.0747                                  108 mL                                      105 mL                                           650 mL                                               52.5%    10   4.33  3.00                   2.40 DETA                          1.20                              0.0756                                  108 mL                                      100 mL                                           650 mL                                               50.5%    11   6.80  3.00                   2.66 DETA                          0.69                              0.0865                                  108 mL                                      102 mL                                           450 mL                                               60.4%    12   6.00  2.00                   1.60 TEPA                          0.80                              0.1207                                   72 mL                                       54.5 mL                                           570 mL                                               50.8%    13   6.00  2.00                   1.60 TETA                          0.80                              0.0959                                   72 mL                                       61 mL                                           570 mL                                               48.1%    14   6.80  2.00                   1.77 MBAPA                          0.46                              0.0914                                   72 mL                                       63 mL                                           500 mL                                               51.9%    15   3.67  2.00                   1.50 MBAPA                          1.00                              0.0698                                   72 mL                                       61 mL                                           500 mL                                               51.6%    __________________________________________________________________________     .sup.1 Measured at 25° C. in 1.0 M NH.sub.4 Cl at a concentration     of 2.00 g/dL.

FIG. 2 shows the variation between theoretical and actual molecularweight for prepolymers of the invention. The theoretical molecularweight is set forth as DP_(n) ; the actual molecular weight is stated asreduced specific viscosity, measured as deciliters per gram (dL/g) at25° C. in 1.0 M NH₄ Cl at a concentration of 2.00 g/dL.

The points plotted in the graph are based on the data from Examples2-11, and the curve is created from these points. As this curvedemonstrates, there is a good correlation between actual molecularweight, measured as reduced specific viscosity, and theoreticalmolecular weight, measured as DP_(n).

Particularly, this correlation can be expressed by the followingformula:

    RSV=a DP.sub.n !.sup.b

The values of a and b depend upon the identity of the diacid or diacidderivative, polyamine, and endcapping agent. For a prepolymer preparedfrom adipic acid, diethylenetriamine, and monoethanolanine, a=0.0459 andb=0.325.

SYNTHESIS OF THE RESINS

The prepolymers of Examples 1-15 were used to prepare the resins ofExamples 16-30, respectively. The prepolymers of Examples 2 and 9 wereused to prepare the resins of Examples 31 and 34, while the Example 10prepolymer was employed in preparing the resins of both Example 32 andExample 33.

Prepolymer, intralinker, and water were added to a 500 ml. 4-neckedflask fitted with a condenser, addition funnel, thermocouple, andmechanical stirrer. The temperature of the mixture was raised to 60° C.and viscosity was monitored using Gardner-Holdt tubes while thetemperature was held at this point.

For Examples 16-21, 26-31, and 33, the reaction was conducted as asingle step. Specifically, cold dilution water was added to cool thereaction to room temperature when the terminal viscosity was reached.

In the case of Examples 22-25, 32, and 34, the resin was prepared by amultistep dilution procedure. After an initial Gardner-Holdt viscosityof "L" was reached, warm water (about 60° C.) was added, and thereaction was continued until a Gardner-Holdt viscosity of "L" wasreached a second time. Warm water was added once more, with the reactionagain being continued until a third predetermined viscosity value wasreached; for Examples 22-25 and 32, this was the terminal viscosity.

In the case of Example 34, warm water was added yet again, and thereaction was continued until a Gardner-Holdt viscosity of "L" wasreached. This fourth viscosity value was the terminal viscosity forExample 34.

At the point of terminal viscosity the reaction was diluted with coldwater, and cooled to room temperature. A light gold product was thuslyprovided.

Table 3 below sets forth the amounts of prepolymer (g/g solids/eq) andintralinker (g/moles) employed in preparing the intralinkedpolyamidoamines of Examples 16-34. Table 3 also sets forth the solidscontent, pH, and Brookfield viscosity (in centipoises) of the product,as well as the above-noted Gardner-Holdt reaction points and reducedspecific viscosity of the resin.

Further in Table 3, the Max. % intralinker value also denotes the amountof intralinker used in the foregoing Examples; yet additionally, it isthe maximum amount of the intralinker which can be reacted with theindicated prepolymer, without causing the resin to gel or resulting in aresin with reactive intralinker functionality. This measurement isaccordingly provided as a mole percent of the intralinker, based on theintralinker reactive amine groups in the prepolymer--i.e., it iscalculated as the molar percent of the indicated intralinker reactiveamine functionality. The resulting value thusly expresses, as apercentage, the relationship of moles of intralinker per mole ofintralinker reactive amine groups in the prepolymer.

                                      TABLE 3    __________________________________________________________________________    Synthesis of Resins             Charge    Example         Prepol             Prepolymer;                      Intratinker;                               Max. %                                     Water    Number         Ex. #             g/g solids/eq.sup.1                      g/moles.sup.2                               Intralinker                                     (mL)    __________________________________________________________________________    16   1    95.98/47.99/0.225                       1.04/0.01125 epi                                5.0% Epi                                      70    17   2    95.41/47.99/0.225                       4.16/0.045 epi                               22.8% Epi                                      60    18   3    91.72/54.76/0.225                       3.64/0.0394 epi                               15.1% Epi                                     100    19   4   131.60/65.41/0.225                       7.80/0.0843 epi                               37.5% Epi                                     100    20   5   140.84/72.68/0.25                       8.10/0.0875 epi                               35.0% Epl                                     120    21   6   150.48/76.59/0.25                      10.41/0.1125 epi                               42.5% Epi                                     115    22   7   130.93/67.82/0.25                       6.94/0.075 epi                               30.0% Epi                                     108    23   8   133.77/67.82/0.25                       6.94/0.075 epi                               30.0% Epi                                     108    24   9   131.69/67.82/0.25                       7.31/0.079 epi                               31.0% Epi                                     108    25   10  134.3G/67.82/0.25                       6.94/0.075 epi                               30.0% Epi                                     108    26   11   90.52/54.68/0.225                       4.16/0.045 epi                               30.0% Epi                                     100    27   12   98.23/49.90/0.50                       3.47/0.0375 epi                                7.5% Epi                                      80    28   13  133.27/64.1/0.50                       5.78/0.0625 epi                               12.5% Epi                                      80    29   14  117.89/61.18/0.20                       4.63/0.05 epi                               25.0% Epi                                     100    30   15  138.31/71.37/0.20                       7.78/0.084 epi                               42.0% Epi                                     115    31   2    95.41/47.99/0.225                       6.87/0.0197 EGG                                8.8% EGD                                      60    32.sup.5         10  134.3/67.82/0.25                      11.50/0.0569 BDD                               22.0% BDD                                     115    33   10  134.30/67.82/0.25                      14.10/0.055 CHD                               22.0% CND                                     115    34   9   129.18/67.82/0.252                      10.62/0.050 BDD                               20.0% BDD                                     115    __________________________________________________________________________    Example         Time- Resin                   Added Water                         B.V.                            Resin    Number         min..sup.3               G-H (ml)  (cPs)                            RSV (dL/g).sup.4                                  pH  Solids    __________________________________________________________________________    16   240   F   82    23.0                            0.2114                                  9.42                                      18.4%    17   120   L   82    54.1                            0.3466                                  8.46                                      20.6%    18   128   L   150   30.6                            0.3415                                  8.82                                      16.1%    19   240   C   50    23.5                            0.1239                                  7.50                                      25.8%    20   240   C   135   16.0                            0.1256                                  7.79                                      19.6%    21   470   D   120   25.0                            0.1421                                  7.13                                      21.8%    22   325/135/155               L, L, G                   50/75/125                         54.6                            0.4738                                  7.92                                      14.6%    23   259/49/42               L, L, L                   50/75/125                         314                            0.7183                                  7.9 13.5%    24   300/65/60               L, L, L                   50/75/125                         138                            0.6416                                  7.98                                      14.5%    25   272/58/48               L, L, L                   50/75/125                         138                            0.6990                                  8.12                                      14.2%    26   147   L   150   35.1                            0.4038                                  8.41                                      16.1%    27   240   G    30   36.1                            0.2334                                  9.27                                      22.0%    28   240   F    30   53.4                            0.1825                                  8.51                                      27.5%    29   102   L   150   43.1                            0.3677                                  9.87                                      17 2%    30   470   C   150   16.6                            0.1486                                  9.82                                      19.5%    31   75    L   82    73.5                            0.3218                                  9.52                                      21.9%    32.sup.5         37/13/38               L, L, L                   50/75/125                         133                            0.6575                                  9.61                                      14.9%    33   519   F   250   14.0                            0.1434                                  9.65                                      15.5%    34   245/67/16/5               L, L, L,                   48/75/75/50                         174                            0.7355                                  10.23                                      15.0%               L    __________________________________________________________________________     .sup.1 Grams of prepolymer solution/grains of solid prepolymer/total     equivalents of intralinker reactive amine in prepolymer.     .sup.2 Grains intralinker/moles intralinker;     epi = epichlorohydrin;     EGD = ethylene glycol diglycidyl ether;     BDD = 1,4butanediol diglycidyl ether;     CHD = 1,4cyctohexanedimethanol diglycidyl ether.     .sup.3 Time for reaction mixture to reach viscosity after temperature     reaches 60° C.     .sup.4 Measured at 25° C. in 1.0 M NH.sub.4 Cl at a concentration     of 2.00 g/dL.     .sup.5 Reaction was run at 50° C. instead of 60° C.

As evidenced in Table 3, the maximum amount of intralinker which can beemployed, without causing gelling or resulting in reactive intralinkerfunctionality, increases as the prepolymer molecular weight decreases.In FIG. 3, maximum percent intralinker is plotted as a function ofprepolymer molecular weight for Examples 17-26. The resulting plot givesgood correlation with the following formula:

    Max. % Intralinker=a RSV!.sup.b

This formula accordingly expresses the relationship between maximumamount of intralinker and prepolymer molecular weight. The values for aand b depend upon the identity of the diacid or diacid derivative,polyamine, endcapping agent, and intralinker. For an intralinkedpolyamidoamine prepared from adipic acid, diethylenetriamine,monoethanolamine, and epichlorohydrin, a=0.0135 and b=-2.97.

FIG. 4 shows the relationship between maximum amount of intralinker and1/(DP_(n) -1) for Examples 17-26; the points plotted on the graph arefrom these Examples, with the Max. % intralinker values having beenconverted to moles of intralinker per mole of intralinker reactive aminegroups in the prepolymer. The resulting curve demonstrates thecorrespondence between maximum intralinker and 1/(DP_(n) -1).

DETERMINATION OF THERMOSETTABILITY

The relative degree of thermosettability of different dried resinsamples was determined by swelling in water; in this context,thermosettability refers to the interconnections between discrete resinmolecules, as discussed herein, which characterize gelling andthermosetting. As noted in P. J. Flory, Principles of Polymer Chemistry,pp. 576-589, Cornell University Press, Ithaca, N.Y. (1953)--which isincorporated herein in its entirety, by reference thereto--the degree ofthermosettability of a material is inversely proportional to its degreeof swelling in a good solvent--e.g., water. A nonthermosetting resinwill be free, or at least substantially or essentially free, ofintermolecular connections between discrete resin molecules, and willdissolve completely in a good solvent.

For instance, in the following procedure the period of time for allowingdissolution of the resins being tested was 24 hours. However, it isunderstood that the nonthermosetting resins of the invention are notlimited to those which dissolve thusly within 24 hours, and thereforeinclude nonthermosetting resins which dissolve completely within timeperiods greater than 24 hours.

Films were prepared from aqueous solutions of different prior artpolyamidoamine-epichlorohydrins, and from an aqueous solution of a resinof the present invention. The films were prepared by drying thesesolutions in aluminum pans 3" in diameter.

In each instance, an amount of the resin solution having a total solidscontent of 11.00 g was placed in the pan, which was heated in a Blue MStabil-Therm forced air oven (Blue M Electrical Company, Blue Island,Ill.) according to the following procedure:

    ______________________________________    First Day          4 hours at 35° C.;                       4 hours at 40° C.;                       16 hours at 45° C.;    Second Day         4 hours at 50° C.;                       4 hours at 60° C.;                       16 hours at 80° C.    ______________________________________

At this point the film sample was cooled to room temperature in adesiccator. The resulting film was about 2.4 mm thick.

A sample of the film weighing between 0.4 and 0.6 g was weighed to0.0001 g, and was added to 100 mL of deionized water in a bottle. After24 hours, the contents of the bottle were poured through a tared steelmesh funnel (˜50 mm diameter ×50 mm high, 100 mesh monel steel); toensure that all of the sample had been removed, the bottle was thenrinsed with deionized water, which was also poured through the funnel.Excess water was removed from the funnel by patting the underside of thefunnel with tissue paper. If a swollen (i.e, with water) sample wasthusly obtained, this sample was accordingly collected in the funnel.

The mass of collected material was then measured to 0.0001 g by weighingthe funnel, and comparing this result to the mass of the funnel beforethe bottle contents were poured therethrough. The swelling ratio ofcollected sample was calculated as the mass of water held by the sampleper unit mass of dry sample, according to the following equation:

    Q= M-M(O)!/M(O)

wherein Q is the swelling ratio, M(O) is the mass of the sample asmeasured after drying, and M is the mass of the sample as measured after24 hours in deionized water.

The results of the foregoing testing are listed in Table 4 below. Asevidenced in this Table, the prior art resins all became insolubilizedupon drying, and exhibited a measurable swelling ratio. The resin ofExample 22 herein was completely dissolved in water in 24 hours, andthus did not thermoset upon drying.

                  TABLE 4    ______________________________________    Water Swelling of Polyamidoamine-Epichlorohydrin Resins                 Weight of  Solids Content of                                        Swelling    Resin        Resin Solution                            Resin Solution                                        Ratio (Q)    ______________________________________    Example 22   75.34 g    14.6%       Infinite    U.S. Patent 2,926,154;                 88.00 g    12.5%       5.92    Example 1    Canadian Patent 979,579;                 88.71 g    12.4%       13.9    Example 1    U.S. Patent 5,338,807;                 45.27 g    24.3%       23.1    Example 1    ______________________________________

Finally, although the invention has been described with reference toparticular means, materials, and embodiments, it should be noted thatthe invention is not limited to the particulars disclosed, and extendsto all equivalents within the scope of the claims.

What is claimed is:
 1. A process for preparing an intralinkedpolyamidoamine which is nonthermosetting and endcapped, comprisingreacting at least one dicarboxylic acid or dicarboxylic acid derivative,at least one polyamine, at least one endcapping agent, and at least oneintralinker.
 2. The process of claim 1 comprising:(a) reacting the atleast one dicarboxylic acid or dicarboxylic acid derivative, at leastone polyamine, and at least one endcapping agent to form an endcappedpolyamidoamine prepolymer; and (b) reacting the endcapped polyamidoamineprepolymer with the at least one intralinker.
 3. The process of claim 2wherein:(a) the endcapped polyamidoamine prepolymer has a DP_(n) ofabout 2 to about 50, is free or substantially free of amine and carboxylend groups, and comprises:(i) alternating dicarboxylic acid andpolyamine residues; and (ii) endcaps lacking carboxyl and aminefunctionality; and (b) the mole ratio of the at least one intralinker,to intralinker reactive amine groups in the endcapped polyamidoamineprepolymer, is between about 1/2 1/(DP_(n) -1)! and about 1/(DP_(n) -1).4. The process of claim 3 wherein the at least one endcapping agentcomprises at least one member selected from the group consisting ofmonofunctional amines, monofunctional carboxylic acids, andmonofunctional carboxylic acid esters.
 5. The process of claim 2 whereinthe ratio of total amidization reactive carboxyl groups to totalamidization reactive amine groups, of the at least one dicarboxylic acidor dicarboxylic acid derivative, at least one polyamine, and at leastone endcapping agent, is about 1:1.
 6. The process of claim 5wherein:(a) the ratio of total dicarboxylic acid or dicarboxylic acidderivative amidization reactive carboxyl groups, to total polyamineamidization reactive amine groups, is sufficiently greater than 1:1 sothat the endcapped polyamidoamine prepolymer, formed by reacting the atleast one dicarboxylic acid or dicarboxylic acid derivative, at leastone polyamine, and at least one endcapping agent, has a DP_(n) of about2 to about 50; (b) the at least one endcapping agent comprises at leastone monofunctional amine; and (c) the total dicarboxylic acid ordicarboxylic acid derivative amidization reactive carboxyl groups isabout equal to the sum of the total polyamine and total endcapping agentamidization reactive amine groups.
 7. The process of claim 6 wherein themole ratio of the at least one intralinker, to intralinker reactiveamine groups in the endcapped polyamidoamine prepolymer, is betweenabout 0.02 and 0.5.
 8. The process of claim 6 wherein the mole ratio ofthe at least one intralinker, to intralinker reactive amine groups inthe endcapped polyamidoamine prepolymer, is between about 1/2 1/(DP_(n)-1)! and about 1/(DP_(n) -1).
 9. The process of claim 8 wherein theendcapped polyamidoamine prepolymer has a DP_(n) of about 3 to about 25.10. The process of claim 9 wherein the endcapped polyamidoamineprepolymer has a DP_(n) of about 3 to about
 10. 11. The process of claim8 wherein:(a) the at least one dicarboxylic acid or dicarboxylic acidderivative comprises at least one member selected from the groupconsisting of dicarboxylic acids; (b) the at least one polyaminecomprises at least one member selected from the group consisting ofpolyalkylene polyamines having:(i) at least two primary amine groups,and (ii) at least one member selected from the group consisting ofsecondary amine groups and tertiary amine groups; and (c) the at leastone intralinker comprises at least one member selected from the groupconsisting of epichlorohydrin, epibromohydrin, diepoxides, diacrylates,dimethacrylates, diacrylamides, and dimethacrylamides.
 12. The processof claim 11 wherein:(a) the at least one dicarboxylic acid ordicarboxylic acid derivative comprises adipic acid; (b) the at least onepolyamine comprises at least one member selected from the groupconsisting of diethylenetriamine, triethylenetetramine,tetraethylenepentamine, and N-methyl-bis(aminopropyl)amine; and (c) theat least one intralinker comprises at least one member selected from thegroup consisting of epichlorohydrin, ethylene glycol diglycidyl ether,1,4-butanediol diglycidyl ether, and 1,4-cyclohexanedimethanoldiglycidyl ether.
 13. The process of claim 12 wherein the endcappingagent comprises monoethanolamine.
 14. The process of claim 5 wherein:(a)the ratio of total polyamine amidization reactive amine groups, to totaldicarboxylic acid or dicarboxylic acid derivative amidization reactivecarboxyl groups, is sufficiently greater than 1:1 so that the endcappedpolyamidoamine prepolymer, formed by reacting the at least onedicarboxylic acid or dicarboxylic acid derivative, at least onepolyamine, and at least one endcapping agent, has a DP_(n) of about 2 toabout 50; (b) the at least one endcapping agent comprises at least onemonofunctional carboxylic acid; and (c) the total polyamine amidizationreactive amine groups is about equal to the sum of the totaldicarboxylic acid or dicarboxylic acid derivative and total endcappingagent amidization reactive carboxyl groups.
 15. The process of claim 14wherein the mole ratio of the at least one intralinker, to intralinkerreactive amine groups in the endcapped polyamidoamine prepolymer, isbetween about 0.02 and 0.5.
 16. The process of claim 14 wherein the moleratio of the at least one intralinker, to intralinker reactive aminegroups in the endcapped polyamidoamine prepolymer, is between about 1/21/(DP_(n) -1)! and about 1(DP_(n) -1).
 17. The process of claim 16wherein the endcapped polyamidoamine prepolymer has a DP_(n) of about 3to about
 25. 18. The process of claim 17 wherein the endcappedpolyamidoamine prepolymer has a DP_(n) of about 3 to about
 10. 19. Theprocess of claim 16 wherein:(a) the at least one dicarboxylic acid ordicarboxylic acid derivative comprises at least one member selected fromthe group consisting of dicarboxylic acids; (b) the at least onepolyamine comprises at least one member selected from the groupconsisting of polyalkylene polyamines having:(i) at least two primaryamine groups, and (ii) at least one member selected from the groupconsisting of secondary amine groups and tertiary amine groups; and (c)the at least one intralinker comprises at least one member selected fromthe group consisting of epichlorohydrin, epibromohydrin, diepoxides,diacrylates, dimethacrylates, diacrylamides, and dimethacrylamides. 20.The process of claim 19 wherein:(a) the at least one dicarboxylic acidor dicarboxylic acid derivative comprises adipic acid; (b) the at leastone polyamine comprises at least one member selected from the groupconsisting of diethylenetriamine, triethylenetetramine,tetraethylenepentamine, and N-methyl-bis(aminopropyl)amine; and (c) theat least one intralinker comprises at least one member selected from thegroup consisting of epichlorohydrin, ethylene glycol diglycidyl ether,1,4-butanediol diglycidyl ether, and 1,4-cyclobexanedimethanoldiglycidyl ether.